Difference Between LCD and LED

There are several advantages and disadvantages of using LCD TVs that are as follows:

Advantages:

• They are lightweight, thin, and compact when compared to bulky CRT displays.

• It has no geometric distortion.

• Perfect sharpness and no bleeding or smearing.

• The screens are perfectly flat.

• No screen burn-in effect.

• Low power consumption. It uses less than half of the power a CRT monitor of the same size would. 

• Little heat is emitted during operation because of less consumption of power.

• Unaffected by magnetic fields.

• The ability to have little or no flicker depends on backlight technology.

• Emits almost no undesirable electromagnetic radiation.

• Can be made in almost any size or shape.

• No theoretical resolution limit. Each additional LCD panel increases the total resolution of the display.

• Can be made in large sizes of over 80-inch.

• LCD grids mask the effects of spatial and grayscale quantization, making the image quality feel higher.

Disadvantages:

• Lifespan gets affected by Direct current flow. Therefore, an Alternating current is supplied for its longevity.

• In high-temperature environments, the contrast gets affected.

• More electricity consumption.

• Not suitable for very bright environments like in sunlight, you can’t view the perfect images.

• Displays only one native resolution. 

• Limited viewing angle, especially in some older or cheaper monitors. This causes colour, saturation, contrast and brightness to vary with the position of the user viewing it.

• Dead or stuck pixels may occur after a period of use. 

• Uneven backlighting in some monitors.

• Black levels may not be as dark as required as the liquid crystals are unable to totally block all of the backlights from passing through.

• Fixed bit depth (also called colour depth). 

• Input lag, because the LCD's A/D converter waits for each frame to be completely put out before drawing it to the LCD panel. 

• Constant use can cause thermalization where part of the screen gets overheated and begins to discolour compared to the rest of the screen.

• Loss of brightness and much slower response times in low-temperature environments. 

• Loss of contrast in high-temperature environments.

Since the power dissipation is less in LED TVs. They can run with greater energy efficiency. They provide a clearer and better picture than the general LCD TVs because these TVs work with a colour wheel or distinct RGB (red, green, blue) coloured lights to produce more realistic and sharper colours.

Liquid Crystal Display was invented in 1968 by electrical engineer George Heilmeier, then working at the RCA laboratories, and his team of scientists. Heilmeier developed the first operational liquid-crystal display based on the dynamic scattering mode (DSM), as he termed it.

In the late 1960s, George William Gray and his team at the University of Hull discovered cyanobiphenyl liquid crystals that had the correct stability and temperature properties for application in LCDs.

In 1970 in Switzerland, Hoffmann-LaRoche, along with inventors Wolfgang Helfrich and Martin Schadt filed for the patent for the twisted nematic field effect (TN) in liquid crystals. They licensed the invention to Swiss manufacturer Brown, Boveri & Cie, which then produced TN displays for wristwatches and other applications for the international markets. Following this, the Japanese electronics industry soon produced the first digital quartz wristwatches with TN-LCDs and numerous other products. 

In 1980, the first color LCD televisions were developed as handheld TVs in Japan. Hattori Seiko's R&D group started developing color LCD pocket televisions back then.

In 1984, Epson released the ET-10, the first full-color, pocket LCD television. The same year, Citizen Watch, introduced the Citizen Pocket TV, a 2.7-inch color LCD TV, with the first commercial TFT LCD display.

After a lot of pioneering work and innovations throughout the world in the 80s and 90s, in 2007 the image quality of LCD TVs finally surpassed the image quality of cathode-ray-tube-based (CRT) TVs.

Display devices (televisions, computer monitors, smartphones etc.) comprise thousands or millions of individual pixels, depending on the type of display. The pixels perform their intended function by changing colour in response to the image being projected. But at times a pixel can die.

This means that the pixel on the display device can no longer change colour. Dead pixels remain black, regardless of the image that is being displayed. Dead pixels easily stick out and can be spotted by turning the display to a white or bright image. 

Mostly the dead pixels are a result of a failed power connection. Pixels require power to change colour. If the power connection to a pixel is cut off, it will become black, and thus a dead pixel.

Dead pixels are different from stuck pixels. Stuck pixels also don’t change colour, just like the dead pixels, but are still receiving energy. So they generally tend to fix themselves over time. While dead pixels are black, the stuck pixels are generally red, green or blue.

Stuck pixels are generally a result of LCD screen manufacturing defects, technical errors, or compatibility issues with some software applications. Old or unused TVs also could develop stuck pixels.